Foldable RFID device interposer and method
An RFID device interposer has folded ends that bring conductive lead end portions of conductive leads of the interposer to an underside of the interposer. The central conductive lead portions of the conductive leads remain on an upper surface of a dielectric substrate of the interposer. The folded ends of the interposer may be held together with an adhesive, or with thermal compression bonding. The interposer may also have an additional conductive material layer on an underside of the dielectric substrate. The conductive material layer may be capacitively coupled to the conductive leads of the interposer. The interposer may be tuned by varying the pressure used to secure the folded ends. This may be used to provide a better impedance match between a chip of the interposer, and the conductive leads and an antenna to which the interposer is coupled.
1. A method of making an interposer for a RFID device, the method comprising:
forming conductive leads on a top surface of a dielectric substrate;
folding substrate end portions and conductive lead end portions underneath a central substrate portion; and
securing the substrate end portions and the conductive lead portions in a folded configuration.
2. The method of claim 1 , wherein the securing includes thermal compression bonding of the substrate end portions in the folded configuration.
3. The method of claim 2 , wherein the thermal compression bonding is part of a process of tuning the interposer.
4. The method of claim 3 , wherein the tuning includes adjusting thickness of folded ends of the interposer to achieve desired individualized electrical characteristics of the interposer.
5. The method of claim 4 , wherein the adjusting thickness includes adjusting pressure used in the thermal compression bonding.
6. The method of claim 4 , wherein the adjusting thickness changes a distance between the conductive leads and a conductive layer that is attached to a bottom surface of the dielectric substrate.
7. The method of claim 6 , wherein the folding includes folding the substrate end portions and the conductive lead end portions over at least part of a bottom surface of the conductive layer.
8. The method of claim 7 , wherein the folding includes folding the substrate end portions to cover substantially all of the bottom surface of the conductive layer.
9. The method of claim 1 , wherein the securing includes adhesively bonding the substrate end portions in the folded configuration.
10. The method of claim 1 , wherein the folding includes tuning the antenna by selectively choosing folding locations on the interposer.
11. A method of tuning an interposer for a RFID device, comprising the steps of;
providing a dielectric substrate having a top surface and a bottom surface, end portions and a central portion;
placing conductive leads on the top surfaces of the dielectric substrate;
folding the end portions of the dielectric substrate beneath the central portion; and
adjusting thickness of the end portions to achieve a desired electrical characteristic between a chip and the conductive leads.
12. A method as recited in claim 11 , wherein the end portions face downwardly.
13. A method as recited in claim 11 , wherein an antenna is provided on the top surface of the dielectric substrate and beneath the conductive leads.
14. A method as recited in claim 13 , wherein the antenna is capacitively coupled to the conductive leads.
15. A method of making an interposer for a RFID device, comprising the steps of;
providing a dielectric substrate having an upper surface, lower surface, a central portion and end portions;
placing conductive leads on the upper surface of the dielectric substrate and extending across the central portion and between the end portions; and
transitioning the end portions from a substantially planar first configuration to a second configuration in which the end portions are offset from the central portion.
16. A method as recited in claim 15 , wherein an antenna is provided on the top surface of the dielectric substrate and beneath the conductive leads.
17. A method as recited in claim 16 , wherein the antenna is capacitively coupled to the conductive leads.
18. A method as recited in claim 16 , wherein the antenna has multiple turns.
19. A method as recited in claim 15 , wherein the step of transitioning includes adjusting thickness of the folded end to achieve a desired electrical characteristic of the interposer.
20. A method as recited in claim 15 , including a further step of matching impedance between a chip and the conductive leads after the step of placing.